Visited the site of the original 1916 Multnomah Lodge as well as hiked up to look at Mist falls today. The rocks are kind of loose and the wet maple leaves make things kind of slick but if one takes their time the view is enjoyable. I believe that if one is comfortable doing some rock scrambling or light bouldering you can take a side trip off to the right at the last big maple tree just under the falls to find a narrow spot to climb up even higher under the falls. Didn't try it today as i was alone by myself. The old fire place is still mostly intact but is starting to fall apart. With the slick conditions and taking pictures and the side trip to scout a way of climbing even higher i spent 45 minutes total, so it's not a long hike.
The parking area can maybe hold two or three very small cars and is the first small turnout west of the Wahkeena falls Trailhead. Here is a link from where i found out about the little hike http://www.portlandhikersfieldguide.org/wiki/Mist_Falls_Hike